Can repeating and non-repeating FRBs be drawn from the same population?

TL;DR

This paper proposes a unified model for FRB sources, explaining their observed diversity and repetition patterns through a Zipf-like distribution, and shows that survey parameters only mildly affect the observed repeater fraction.

Contribution

It introduces a model-independent framework linking FRB burst rate distribution to observed properties, supporting a single population hypothesis for all FRBs.

Findings

FRB sources follow a Zipf-like distribution of burst rates.

The observed ratio of repeaters to non-repeaters can be explained by this distribution.

Survey sensitivity and duration only mildly influence the observed repeater fraction.

Abstract

Do all Fast Radio Burst (FRB) sources repeat? We present evidence that FRB sources follow a Zipf-like distribution, in which the number density of sources is approximately inversely proportional to their burst rate above a fixed energy threshold-even though both the burst rate and number density span many orders of magnitude individually. We introduce a model-independent framework that predicts the distribution of observed fluences and distances, and repetition rates of an FRB population based on an assumed burst rate distribution per source. Using parameters derived directly from observations, this framework simultaneously explains several key features of the FRB population: (i) The observed ratio of repeaters to apparent non-repeaters; (ii) The much lower ratio of apparent non-repeaters to the total number of Soft Gamma Repeater (SGR) sources within the observable Universe; And (iii) the slightly smaller average distances of known repeaters compared to non-repeaters. We further explore how survey parameters, such as radio sensitivity and observation time, influence these statistics. Notably, we find that the fraction of repeaters rises only mildly with improved sensitivity or longer exposure. This weak dependence could be misinterpreted as evidence that not all FRBs repeat. Overall, our results support the idea that a single population-likely magnetars-can account for the full observed diversity of FRB activity, from very inactive FRB sources like SGR 1935+2154 to the most active repeaters.